|13th March 2007, 07:09 PM||#11|
Join Date: Aug 2001
Location: Ingolstadt Germany
I don´t want to confuse you but here´s another method:
1. Set the output to something like a 5-10V sinus (8 or 4 ohms)
2. Measure the voltage over each current source fet´s source resistors
3. add all of the voltages and devide by the source resistor value. Now you´ve got the current from the current source
4. measure the voltage over the output resistors and devide by their combined value. Now you´ve got the total output current
5. Devide the C.S. current by the total current et voilà the AC-Current-Gain
een ooievaar is geen konijn want zijn oren zijn te klein!
|1st June 2007, 11:48 AM||#12|
Join Date: Oct 2002
Location: Laren NH
Oke did some testing yesterday with the R21. The AC current gain is set properly. The dc bias is almost 2 amps total. With +/- 40V rail i could pull out something about 23,5 Vrms into 8 ohm thus 69 Watt with THD+N under 0,1%.
I also completed the other channel ! But I measured some 50/100 Hz noise from the mains i think on the output.
We have checked the powersupplyconnections with a old tek scope with differential input at the connection between the rectifier diodes and the big caps and measured those nice diode currents voltage drops over these connections. I'll check these next week after i connected these amps to my system !!!
Thanks Nelson and Jaap Pees ( for his test bench and knowledge ) and the others for pointing me in the right direction. Will email you my project for the diypass website soon.
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